Primary Cutaneous Gamma-Delta T Cell Lymphomas: A Case Series and Overview of the Literature.

Silvia Alberti-Violetti,Valentina Merlo,Emilio Berti,Luigia Venegoni,Carlo Alberto Maronese

doi:10.3390/dermatopathology8040054

Abstract

Primary cutaneous gamma-delta T cell lymphomas (PCGDTCLs) are rare and aggressive cutaneous malignancies that have been diagnostically challenging for dermopathologists and clinicians since their first published descriptions in 1991. Since then, the availability of immunostaining for T cell receptors γ and δ in formalin-fixed paraffin-embedded samples has greatly increased our knowledge of the gamma-delta phenotype by showing that it may also be present in the context of indolent entities, such as mycosis fungoides (MFs) and lymphomatoid papulosis, and this has raised questions concerning its diagnostic and prognostic implications. We here describe the histological and clinical differences between the dermo-epidermal and subcutaneous sub-groups of PCGDTCL observed in a cohort of 20 patients attending a single experienced centre, with particular focus on cases with an MF-like presentation, which are still less well defined than those of classic MF.

Highlights

According to the WHO classification of cutaneous neoplasms [1], primary cutaneous gamma-delta T cell lymphomas (PCGDTCLs) are rare and aggressive entities characterised by the clonal cutaneous proliferation of activated mature gamma-delta T cells with a cytotoxic phenotype
The first cases of PCGDTCL were published in 1991 by Berti et al [2], who described a case of disseminated pagetoid reticulosis characterised by an epidermotropic gamma-delta infiltration, and Burg et al [3], who described a case characterised by T cell receptor (TCR) δ-positive subcutaneous plaques without any signs of epidermotropism
The increasing availability of immunomarkers of the δ chain of the TCR in formalin-fixed paraffin-embedded (FFPE) tissue samples over the last few years has extended our knowledge of gamma-delta cutaneous proliferations by showing that such infiltrates can be present in typical alpha/beta lymphoproliferative disorders, in which they play a reactive rather than a malignant role [4]

Summary

Introduction

According to the WHO classification of cutaneous neoplasms [1], primary cutaneous gamma-delta T cell lymphomas (PCGDTCLs) are rare and aggressive entities characterised by the clonal cutaneous proliferation of activated mature gamma-delta T cells with a cytotoxic phenotype. The increasing availability of immunomarkers of the δ chain of the TCR in formalin-fixed paraffin-embedded (FFPE) tissue samples over the last few years has extended our knowledge of gamma-delta cutaneous proliferations by showing that such infiltrates can be present in typical alpha/beta lymphoproliferative disorders, in which they play a reactive rather than a malignant role [4]. This finding has raised questions concerning their prognostic value as their clinical course may be more indolent than the classic course of PCGDTCL [2,5,6]

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Results

Conclusion